The only people who say Shut up are people who can't make good insults so use the same one over, and over.
Josh: Hey how are you?
Shawn: Shut up
Josh: Shut up you big potato looking self how about you get off of the internet and go touch some grass with your big self.
Person 1 : Dude, that’s gay!
Person 2 : Shut up man.
Person 1 : gee ok, you don’t have to be mean about it. Was it that Offensive?
Person 2 : You’re literally gay bro.
Person 1 : Shut up! You can’t be talking your also gay!!